Fresh Science

When black holes rip stars and gas clouds to pieces, the debris gets so hot that it shrouds the black hole with a brilliant blue-white light. Or so everyone thought, until we discovered pink quasars; black holes glowing with a pink light so intense that they are amongst the pinkest objects in the Universe.

A group of Australian astronomers have found that some black holes are bright pink!

Black holes have captured the imagination of the public over the years with some popular depictions in science fiction movies. They have such intense gravity fields that they even suck in light. This is why they appear black… but Dr Paul Francis, a lecturer at the Australian National University, together with Dr Rachel Webster and Dr Michael Drinkwater, from the University of Melbourne’s School of Physics have discovered that some black holes are pink in colour.

The “Pink holes” were discovered using telescopes at Parkes and Coonabarabran in the western plains of NSW between 1994 and 1998. The work will be presented at the “Fresh Science” Conference in Melbourne.

“These pink things were quite easy to find” said Dr Francis. “The hard bit was proving that they are black holes. These black holes are more than a billion light-years away, and are more than one hundred thousand times fainter than the human eye can see. It took the combined power of four of Australia’s best telescopes to identify what they were.”

How could a black hole be pink? “We really don’t have the foggiest idea” said Dr Francis. “We’re pretty certain that it isn’t the black holes themselves that are pink, the pink light is actually coming from gas just outside the black hole. We think that these black holes live in the middle of galaxies, and they are devouring anything that comes near them. Possibly as the mangled remains of space matter, stars and gas clouds swirl down the throat of the black holes, they emit an intense pink light.”

It is well known that massive black holes devour stars and gas. Black holes like this are called quasars, and were first discovered in the 1960s.”Until now”, Dr Francis said, “only blue quasars had been seen, and it was believed that the debris swirling around black holes should emit only blue light, not pink.”

So what is different about these pink quasars? “We’re don’t really know” said Dr Francis. “But we are beginning to suspect that the debris swirling around the black holes is acting as a vast natural radio transmitter, broadcasting intense pink light to the universe.”